A back light unit plays a role of evenly flashing a light to a reverse side of LCD, which does not flash a light on its own, to make a display image be visible, and a light guide plate is a parts performing the brightness of the back light unit and uniform lighting function, and one of plastic molding lens uniformly transferring the emitted light from a light source (LED) to the entire LCD plane.
FIG. 1 is a drawing illustrating a structure of the conventional edge-type back light unit.
As illustrated, the edge-type back light unit has a structure wherein a printed circuit board (10) having a LED light source (20) is arranged to the side part of a light guide plate, and the light emitted from the LED light source (20) is induced by the light guide plate (30) and exited onward.